Wireless communications have become ubiquitous in modern society, and with the ever-increasing demand for bandwidth, there are significant pressures to increase the effective bandwidth in wireless communication systems. One technique for increasing bandwidth in a wireless communication system is to employ spatial diversity, where different data streams are transmitted from multiple transmit antennas to multiple receive antennas of a receiving device. The data streams may be transmitted from different devices that have a single antenna, from a single device that has multiple antennas, or any combination thereof. Systems that use multiple transmit antennas and multiple receive antennas are generally referred to as Multiple Input Multiple Output (MIMO) systems.
Certain MIMO systems are configured to employ spatial multiplexing, where the different data streams are transmitted at the same time using the same communication resource, such as a particular carrier or sub-carrier. Although each data stream is only transmitted from one transmit antenna, all of the data streams are received at each of the multiple receive antennas. The different data streams propagate over different paths and tend to interfere with one another as they are transmitted from the respective transmit antennas to the receive antennas. As such, a different aggregation of all of the transmitted data streams is received at each of the receive antennas.
To recover each of the originally transmitted data streams from the aggregated signals that are received at each of the receive antennas, the receiving device employs a MIMO decoder. The MIMO decoder essentially processes the aggregated signals to extract each of the originally transmitted data streams. This extraction process is computationally intensive and involves significant amounts of matrix manipulation, such as matrix addition, subtraction, division, inversion, and the like. To further complicate matters, these computations are iterative in nature and generally need to be provided on a symbol-by-symbol basis for each of the transmitted data streams.
While wireless systems are expected to provide ever-higher performance to meet consumer demand, equipment providers are under continuous pressure by service providers and consumers to provide the performance enhancements at lower costs. Unfortunately, computational power and the costs are directly related. Since MIMO decoding is one of the most computationally intensive processes in a MIMO receiver, there is a need for a technique to reduce the complexity of the computations for the extraction process provided by the MIMO decoder. There is a further need to reduce the complexity of the computations without negatively impacting the overall performance of the MIMO receiver.